Indwelling catheters and other devices are commonly implanted into patients for varying lengths of time and used for many medical procedures including therapeutic and diagnostic fluid delivery and aspiration of excess fluid and are well known in the art. The simplest such devices typically allow the exit of fluid through a single opening located at the distal tip of a needle. A needle presents problems wherein relatively high pressure fluid is delivered and has a highly concentrated distribution near the opening and typically does not leach out to more distant locations. An attempt to improve the delivery of fluid includes catheters having a plurality of openings at various axial positions along the distal portion of the catheter. The effectiveness of such devices for some procedures is limited due to uneven weep rates resulting from higher fluid pressure in the area of the proximal holes than at more distal holes. A further disadvantage of such catheter-like devices is that they are inherently relatively soft and therefore require a guidewire, guide catheter, cannula, trocar or other type of introducer to initially position the device prior to treatment. Being forced to use additional introducing devices necessitates longer treatment times, increased expense and a greater probability of infection. In addition, the need for introducing devices increases the size of tissue access opening to the treatment site, thereby increasing the morbidity, invasiveness and pain associated with the procedure. Other catheters provide for a more uniform weep rate by having an infusion catheter with an outer tube and a concentrically enclosed inner tube, and a central lumen in the inner tube. Both the outer and inner tubes are provided with a plurality of openings along a distally located infusion section which even the longitudinal distance the fluid must flow before being infused into a patient. As discussed above, this and similar catheters are inherently relatively soft and therefore require a guidewire, guide catheter, cannula, trocar or other type of introducer to initially position the device prior to treatment.
The recent advent of Botox® treatment for the elimination of wrinkles in ageing skin is ordinarily performed by a physician injecting the treatment area with diluted amounts of the toxin produced by the bacterium Clostridium botulinum. The toxin is typically injected beneath the skin into specific muscles using a conventional needle attached to a syringe, which results in a relatively concentrated amount of toxin in a small area, with reduced amounts leaching to more distant locations. The affected muscles are weakened in a controlled manner thereby temporarily being unable to contract, giving the appearance of a skin wrinkle disappearing. For purposes of Botox® treatment as well as many other medical procedures, it would be extremely desirable to have a temporarily implantable device that is inherently rigid so as to be self-introducing, which allows the uniform distribution of therapeutic fluids over a relatively large surface area. Also desirable would be a self-introducing device that could be used under negative pressure to aspirate or remove excess body fluid from a region of a patient's body. A single device that could evenly distribute effective concentrations of a therapeutic fluid over an extended area and also used to aspirate excess fluid amounts would be even more desirable.
Hollow fibers are made from porous polymers that were developed to improve the distribution of drugs administered directly into the central nervous system. It has been found that using a porous polymer hollow fiber significantly increases the surface area of brain tissue that the drug or therapeutic fluid is infused into. Dye was infused into a mouse brain by convection-enhanced delivery using a 28 gauge needle compared to a hollow fiber having a 3 mm length. Hollow fiber mediated infusion increased the volume of brain tissue labeled with dye by a factor of 2.7 times compared to using a needle. In order to determine if hollow fiber use could increase the distribution of gene therapy vectors, a recombinant adenovirus expressing the firefly luciferase reporter was injected into the mouse striatum. Gene expression was monitored using in vivo luminescent imaging. In vivo imaging revealed that hollow fiber mediated infusion of adenovirus resulting in gene expression that was an order of magnitude greater than when a conventional needle was used for delivery. To assess distribution of gene transfer, an adenovirus expression green fluorescent protein was injected into the striatum using a hollow fiber and a conventional needle. The hollow fiber greatly increased the area of brain transduced with adenovirus relative to a needle, transducing a significant portion of the injected hemisphere.